ROSEMEAD, Calif. – Valentine’s Day is a day full of sweet sentiments, but Southern California Edison (SCE) reminds customers of a situation that can turn things sour fast: floating Mylar balloons.

Helium-filled Mylar balloons, often given as Valentine’s gifts, can float into power lines and cause power outages or even downed power lines. The resulting outages can last from minutes to hours for homes and businesses, and can lead to inoperable stoplights, property damage and possibly even injuries.

In the last two years, SCE has seen a sharp increase in balloon-related outages, with 689 last year after 583 in 2012. These are the highest numbers since 2007. In addition, there was a 75-percent jump in balloon-caused outages between February (59), when the numbers usually spike, and January (34) last year.

SCE asks customers to keep the balloons indoors, and if they are used outdoors, to keep them secured to a heavy weight to keep them from floating away (It is unlawful to sell balloons without a string weight). Never remove the weight. Mass balloon releases also are illegal in several states, including California.

“It only takes one wayward balloon to cause a power outage,” said Don Neal, SCE director of Corporate Environmental Health and Safety. “Tying down a Mylar balloon is the best way to prevent this.”

SCE recommends some other safety tips for handling Mylar balloons:

Do not attempt to retrieve a balloon – or any foreign object – tangled in power lines. Instead, call SCE at 800-611-1911 and report the problem.

Never tie a Mylar balloon to a child’s wrist. If the balloon comes into contact with electricity, it will travel through the balloon and into the child, causing serious injury or even death.

Never attach streamers to any balloon – latex or metallic.

When done with the balloons, do not release them. Puncture them several times or cut the knot and throw them in the garbage to prevent them from floating away.

If you see a downed line or dangling wire – even if it appears not to be live – don’t touch or approach it and call 911 immediately.

An Edison International (NYSE:EIX) company, Southern California Edison is one of the nation’s largest electric utilities, serving a population of nearly 14 million via 4.9 million customer accounts in a 50,000-square-mile service area within Central, Coastal and Southern California.